THUGS robbed a man before demanding he strip off his clothes while on the Metro.
The 58-year-old passenger was travelling from Sunderland when he was approached by a gang of three men.
One of them threatened him and ordered he hand over his valuables.
He gave them his phone and bag before the thugs left the train at Brockley Whins station.
They stood on the platform before re-boarding the train and ordering the man to strip and hand over all his clothes.
The victim refused and the gang got off the train at Fellgate.
British Transport Police (BTP) have launched an investigation into the incident and have released a CCTV image of a man they would like to speak to in connection with the robbery.
Detective Constable Wayne Green, who is heading the investigation, said: “The victim was threatened if he didn’t comply with his request.
“This was a very intimidating experience for the man, who was very shaken by his ordeal.
“I am urging anyone who may recognise the man in the CCTV image, or have any information that may help people with our inquiries to contact us.”
Richard McClean, managing director of Metro operator DB Regio Tyne and Wear, added: “We have a zero tolerance policy of criminal behaviour perpetrated against passengers or staff on trains or at Metro stations.
“We are fully co-operating with the BTP on this particular case and have provided them with appropriate CCTV images.
“Metro’s CCTV system provides very clear images which can help police to readily identify and consequently find those who have acted unlawfully.”
The robbery took place on Saturday, January 28, between 11.30pm and 11.50pm.
Anyone with information can call BTP on 0800 40 50 40 quoting reference BL10 of 07/02/2012 or Crimestoppers anonymously on 0800 555 111.